In total, Three has scooped up 140MHz of 5G-friendly spectrum which it claims will enable it to offer peak speeds up to twice as fast as any rival network at launch.

“5G is a game-changer for Three, and of course I am excited that we will be the only operator in the UK who can offer true 5G,” said former Three CEO Dave Dyson last June.

With 50MHz of spectrum, Vodafone is Three’s closest rival.

Vodafone, EE, an independent consultant, and three members of the public challenged Three’s advertising that implied rival carriers weren’t offering true 5G services.

In an interview with TechRadar Pro last year, Dyson said: “Of course EE and Vodafone have launched [5G] but the reality is that, whether 100MHz is the standard or not, our 5G service uses double the spectrum and in practice that means double the capacity.”

ASA said it recognised Three’s argument that the ITU states that a true 5G experience requires 100MHz of spectrum. However, the standards agency argued that the limited rollout of 5G networks and supported devices at the time meant that it was unlikely any capacity issues would impact the experience for consumers.

Three must not release further advertising in its current form going forward.